As the art moves towards higher power integrated circuits and components, hereinafter referred to as heat emitting components, heat transfer from the heat emitting components becomes increasingly difficult and more important. One conventional technique used to remove heat from a heat emitting component was to employ a finned heat sink which was placed in thermal contact with the heat emitting component. In this manner, heat generated by the heat emitting component was conducted to the heat sink and then dissipated to the ambient environment.
FIG. 1 is a side plan view of a heat sink structure 10 in accordance with the prior art. Heat sink structure 10 included a finned heat sink 12 in thermal contact with a heat emitting component 14. During use, heat emitting component 14 generated heat. This heat was conducted to heat sink 12, which dissipated this heat to the ambient environment.
Heat sink 12 included a base section 16 and a plurality of fins 18 extending upwards from base section 16. To enhance heat dissipation, a fan 20 was used to draw air between fins 18. Fan 20 included a motor 22 and a propeller 24. Fan 20 was mounted to a top T of heat sink 12 such that a longitudinal axis 20L of fan 20 was perpendicular to base section 16. During use, motor 22 spun propeller 24 drawing air between fins 18 as indicated by arrows 25.
As the art moved towards smaller and lighter weight electronic devices, the spacing between fan 20 and a cabinet 26 was reduced. Generally, cabinet 26 was the housing of the electronic device, e.g., a computer system, which protected the internal components including heat sink structure 10 of the electronic device. Disadvantageously, cabinet 26 impeded airflow through fan 20, which, in turn, restricted airflow between fins 18 of heat sink 12. More particularly, when the spacing between fan 20 and cabinet 26 was small, airflow between fins 18 of heat sink 12 was severely restricted.
To further enhanced heat transfer from heat emitting component 14 and to allow mounting of heat sink 12, the area of heat sink 12 was made substantially greater than the area of heat emitting component 14. More particularly, heat emitting component 14 contacted a central region 30 of base section 16 of heat sink 12. During use, heat was conducted from heat emitting component 14 to central region 30, which was the hottest region of heat sink 12 (hereinafter hottest region 30).
Fan 20 was centrally mounted to heat sink 12 such that motor 22 was aligned with hottest region 30. Of importance, a dead spot 28 of diminished or no airflow existed directly below motor 22. Disadvantageously, hottest region 30, i.e., the hottest region of heat sink 12, was in contact with dead spot 28. As a result, there was ineffective heat transfer from hottest region 30 which significantly diminished the ability of heat sink 12 to dissipate heat from heat emitting component 14.
To prevent failure of heat emitting component 14, it was important that heat emitting component 14 remained below the maximum allowable operating temperature. When the spacing between cabinet 26 and fan 20 was small, a more powerful fan 20 was used to ensure adequate cooling of heat emitting component 14. However, using a more powerful fan 20 increased noise, which was detrimental to the performance of the electronic device, and increased power consumption, which increased the overall operating cost of the electronic device. Further, to avoid excess power consumption and to avoid exceeding noise level limits, the size of fan 20 was severely restricted.